Gao Junhua, Tian Liangliang, Cheng Zhengfu
School of Electronic and Information Engineering, Chongqing University of Arts and Sciences, Chongqing 402160, China.
School of Electronic Engineering, Heilongjiang University, Harbin 150080, China.
Micromachines (Basel). 2025 Feb 18;16(2):231. doi: 10.3390/mi16020231.
The advancement of microfluidic technology has introduced new requirements for the sensitivity of microflow sensors. To address this, this paper presents a novel high-sensitivity thermal microflow sensor incorporating a heat-insulating cavity structure. The sensor utilizes porous silicon as the substrate and employs vanadium dioxide as the thermistor element. This study employed COMSOL Multiphysics finite element software 5.6 to investigate the impact of materials and structural factors on the sensor's sensitivity, as well as considering the dynamic laws governing their influence. Additionally, the effects of thermal expansion and thermal stress on the microstructure of the sensor are thoroughly examined. The research results show that the sensitivity of the sensor was influenced by key factors such as the distance between the heater and the thermistors, the diameter of the flow channel, the power of the heater, and the presence of an insulation cavity. The utilization of B-phase vanadium dioxide, known for its high temperature coefficient of resistance and suitable resistivity, led to a significant reduction in sensor size and a remarkable improvement in sensitivity. The implementation of four thermistors forming a Wheatstone full bridge further enhanced the sensor's sensitivity. The sensor's sensitivity was substantially higher when employing a porous silicon substrate compared with a silicon substrate. Moreover, the integration of a micro-bridge and four micro-beams composed of silicon nitride into the sensor's structure further improved its sensitivity. The proposed design holds promise for enhancing the sensitivity of thermal microflow sensors and offers valuable insights for future advancements in MEMS technology.
微流控技术的进步对微流量传感器的灵敏度提出了新的要求。为解决这一问题，本文提出了一种新型的具有隔热腔结构的高灵敏度热微流传感器。该传感器以多孔硅为基底，采用二氧化钒作为热敏电阻元件。本研究使用COMSOL Multiphysics有限元软件5.6来研究材料和结构因素对传感器灵敏度的影响，并考虑它们影响的动态规律。此外，还深入研究了热膨胀和热应力对传感器微观结构的影响。研究结果表明，传感器的灵敏度受加热器与热敏电阻之间的距离、流道直径、加热器功率以及绝缘腔的存在等关键因素的影响。利用具有高电阻温度系数和合适电阻率的B相二氧化钒，可显著减小传感器尺寸并显著提高灵敏度。采用四个热敏电阻构成惠斯通电桥进一步提高了传感器的灵敏度。与硅基底相比，采用多孔硅基底时传感器的灵敏度显著更高。此外，将由氮化硅组成的微桥和四个微梁集成到传感器结构中进一步提高了其灵敏度。所提出的设计有望提高热微流传感器的灵敏度，并为微机电系统技术的未来发展提供有价值的见解。
